﻿using System;
using System.IO;
using System.IO.Compression;
using System.Text;

namespace Toenda.Foundation.IO.Compression {
	public class NamedGZipStream : DeflateStream {
		private long _size;
		private uint _crc;
		private bool _leaveOpen;
		private Stream _output;
		private string _name;

		public NamedGZipStream(Stream output, string name, bool leaveOpen)
			: base(output, CompressionMode.Compress, true) {
			if(string.IsNullOrEmpty(name)) {
				throw new ArgumentNullException("name");
			}

			_output = output;
			_leaveOpen = leaveOpen;
			_name = name;

			byte[] header = { 0x1f, 0x8b, 0x8, 0x8, 0, 0, 0, 0, 4, 0 };
			_output.Write(header, 0, header.Length);

			byte[] data = Encoding.UTF8.GetBytes(name);
			_output.Write(data, 0, data.Length);
			_output.WriteByte(0);
		}

		public string Name { get { return _name; } }

		public override IAsyncResult BeginWrite(byte[] array, int offset, int count, AsyncCallback asyncCallback, object asyncState) {
			IAsyncResult result = base.BeginWrite(array, offset, count, asyncCallback, asyncState);
			_size += count;
			_crc = UpdateCrc(_crc, array, offset, count);
			return result;
		}

		public override void Write(byte[] array, int offset, int count) {
			base.Write(array, offset, count);
			_size += count;
			_crc = UpdateCrc(_crc, array, offset, count);
		}

		protected override void Dispose(bool disposing) {
			base.Dispose(disposing);

			if(disposing && _output != null) {
				_output.WriteByte((byte)(_crc & 0xff));
				_output.WriteByte((byte)((_crc >> 8) & 0xff));
				_output.WriteByte((byte)((_crc >> 16) & 0xff));
				_output.WriteByte((byte)((_crc >> 24) & 0xff));
				_output.WriteByte((byte)(_size & 0xff));
				_output.WriteByte((byte)((_size >> 8) & 0xff));
				_output.WriteByte((byte)((_size >> 16) & 0xff));
				_output.WriteByte((byte)((_size >> 24) & 0xff));
					
				if(!_leaveOpen) {
					_output.Close();
				}

				_output = null;
			}
		}

		// See RFC1952 for details. http://www.faqs.org/rfcs/rfc1952.html
		private static uint UpdateCrc(uint crc, byte[] buffer, int offset, int length) {
			crc ^= 0xffffffffU;
				
			while(--length >= 0) {
				crc = crcTable[(crc ^ buffer[offset++]) & 0xFF] ^ (crc >> 8);
			}

			crc ^= 0xffffffffU;
			return crc;
		}

		private static readonly uint[] crcTable = new uint[] {  
			0x00000000u, 0x77073096u, 0xee0e612cu, 0x990951bau, 0x076dc419u,
			0x706af48fu, 0xe963a535u, 0x9e6495a3u, 0x0edb8832u, 0x79dcb8a4u,
			0xe0d5e91eu, 0x97d2d988u, 0x09b64c2bu, 0x7eb17cbdu, 0xe7b82d07u,
			0x90bf1d91u, 0x1db71064u, 0x6ab020f2u, 0xf3b97148u, 0x84be41deu,
			0x1adad47du, 0x6ddde4ebu, 0xf4d4b551u, 0x83d385c7u, 0x136c9856u,
			0x646ba8c0u, 0xfd62f97au, 0x8a65c9ecu, 0x14015c4fu, 0x63066cd9u,
			0xfa0f3d63u, 0x8d080df5u, 0x3b6e20c8u, 0x4c69105eu, 0xd56041e4u,
			0xa2677172u, 0x3c03e4d1u, 0x4b04d447u, 0xd20d85fdu, 0xa50ab56bu,
			0x35b5a8fau, 0x42b2986cu, 0xdbbbc9d6u, 0xacbcf940u, 0x32d86ce3u,
			0x45df5c75u, 0xdcd60dcfu, 0xabd13d59u, 0x26d930acu, 0x51de003au,
			0xc8d75180u, 0xbfd06116u, 0x21b4f4b5u, 0x56b3c423u, 0xcfba9599u,
			0xb8bda50fu, 0x2802b89eu, 0x5f058808u, 0xc60cd9b2u, 0xb10be924u,
			0x2f6f7c87u, 0x58684c11u, 0xc1611dabu, 0xb6662d3du, 0x76dc4190u,
			0x01db7106u, 0x98d220bcu, 0xefd5102au, 0x71b18589u, 0x06b6b51fu,
			0x9fbfe4a5u, 0xe8b8d433u, 0x7807c9a2u, 0x0f00f934u, 0x9609a88eu,
			0xe10e9818u, 0x7f6a0dbbu, 0x086d3d2du, 0x91646c97u, 0xe6635c01u,
			0x6b6b51f4u, 0x1c6c6162u, 0x856530d8u, 0xf262004eu, 0x6c0695edu,
			0x1b01a57bu, 0x8208f4c1u, 0xf50fc457u, 0x65b0d9c6u, 0x12b7e950u,
			0x8bbeb8eau, 0xfcb9887cu, 0x62dd1ddfu, 0x15da2d49u, 0x8cd37cf3u,
			0xfbd44c65u, 0x4db26158u, 0x3ab551ceu, 0xa3bc0074u, 0xd4bb30e2u,
			0x4adfa541u, 0x3dd895d7u, 0xa4d1c46du, 0xd3d6f4fbu, 0x4369e96au,
			0x346ed9fcu, 0xad678846u, 0xda60b8d0u, 0x44042d73u, 0x33031de5u,
			0xaa0a4c5fu, 0xdd0d7cc9u, 0x5005713cu, 0x270241aau, 0xbe0b1010u,
			0xc90c2086u, 0x5768b525u, 0x206f85b3u, 0xb966d409u, 0xce61e49fu,
			0x5edef90eu, 0x29d9c998u, 0xb0d09822u, 0xc7d7a8b4u, 0x59b33d17u,
			0x2eb40d81u, 0xb7bd5c3bu, 0xc0ba6cadu, 0xedb88320u, 0x9abfb3b6u,
			0x03b6e20cu, 0x74b1d29au, 0xead54739u, 0x9dd277afu, 0x04db2615u,
			0x73dc1683u, 0xe3630b12u, 0x94643b84u, 0x0d6d6a3eu, 0x7a6a5aa8u,
			0xe40ecf0bu, 0x9309ff9du, 0x0a00ae27u, 0x7d079eb1u, 0xf00f9344u,
			0x8708a3d2u, 0x1e01f268u, 0x6906c2feu, 0xf762575du, 0x806567cbu,
			0x196c3671u, 0x6e6b06e7u, 0xfed41b76u, 0x89d32be0u, 0x10da7a5au,
			0x67dd4accu, 0xf9b9df6fu, 0x8ebeeff9u, 0x17b7be43u, 0x60b08ed5u,
			0xd6d6a3e8u, 0xa1d1937eu, 0x38d8c2c4u, 0x4fdff252u, 0xd1bb67f1u,
			0xa6bc5767u, 0x3fb506ddu, 0x48b2364bu, 0xd80d2bdau, 0xaf0a1b4cu,
			0x36034af6u, 0x41047a60u, 0xdf60efc3u, 0xa867df55u, 0x316e8eefu,
			0x4669be79u, 0xcb61b38cu, 0xbc66831au, 0x256fd2a0u, 0x5268e236u,
			0xcc0c7795u, 0xbb0b4703u, 0x220216b9u, 0x5505262fu, 0xc5ba3bbeu,
			0xb2bd0b28u, 0x2bb45a92u, 0x5cb36a04u, 0xc2d7ffa7u, 0xb5d0cf31u,
			0x2cd99e8bu, 0x5bdeae1du, 0x9b64c2b0u, 0xec63f226u, 0x756aa39cu,
			0x026d930au, 0x9c0906a9u, 0xeb0e363fu, 0x72076785u, 0x05005713u,
			0x95bf4a82u, 0xe2b87a14u, 0x7bb12baeu, 0x0cb61b38u, 0x92d28e9bu,
			0xe5d5be0du, 0x7cdcefb7u, 0x0bdbdf21u, 0x86d3d2d4u, 0xf1d4e242u,
			0x68ddb3f8u, 0x1fda836eu, 0x81be16cdu, 0xf6b9265bu, 0x6fb077e1u,
			0x18b74777u, 0x88085ae6u, 0xff0f6a70u, 0x66063bcau, 0x11010b5cu,
			0x8f659effu, 0xf862ae69u, 0x616bffd3u, 0x166ccf45u, 0xa00ae278u,
			0xd70dd2eeu, 0x4e048354u, 0x3903b3c2u, 0xa7672661u, 0xd06016f7u,
			0x4969474du, 0x3e6e77dbu, 0xaed16a4au, 0xd9d65adcu, 0x40df0b66u,
			0x37d83bf0u, 0xa9bcae53u, 0xdebb9ec5u, 0x47b2cf7fu, 0x30b5ffe9u,
			0xbdbdf21cu, 0xcabac28au, 0x53b39330u, 0x24b4a3a6u, 0xbad03605u,
			0xcdd70693u, 0x54de5729u, 0x23d967bfu, 0xb3667a2eu, 0xc4614ab8u,
			0x5d681b02u, 0x2a6f2b94u, 0xb40bbe37u, 0xc30c8ea1u, 0x5a05df1bu,
			0x2d02ef8du
		};
	}
}
